The present invention relates to a process for the production of oxygenated fuel blending compositions by the hydration of olefins. Specifically, the invention relates to a process for the hydration of propylene to produce isopropanol for blending into gasoline.
As is well known, alkylation can produce a premium grade gasoline component from olefins by reaction with isoparaffins such as isobutane or isopentane. Refineries have, however, experienced a shortage of isoparaffins, particularly isobutane, and therefore have an excess of olefins. So a way to place these olefins into the motor gasoline pool is needed. At the same time, gasoline octane requirements have increased and the use of traditional lead-containing gasoline additives has been largely discontinued. It has, therefore, become necessary to find alternative means to produce high octane fuel compositions without the necessity for alkylation. This may be accomplished by producing oxygenated compounds, e.g., isopropanol from the excess olefins.
Furthermore, some gasolines have a maldistribution of high octane components and when used without fuel injection can knock under driving conditions not predicted by model octane testing. Addition of isopropanol to such gasolines provides a good way to improve octane component distribution.
Isopropanol may be made with very high propylene conversions per pass using even dilute C.sub.3 olefin-containing feedstocks at low space velocities. Under these conditions, however, especially at low water to olefin molar feed ratios, large amounts of diisopropyl ether (DIPE) may be formed. The present process relates particularly to the treatment of the DIPE by-product so that the isopropanol production process can be conducted more efficiently.